The embodiments relate to cardiac assist devices that comprise a jacket that wraps the exterior of the heart, where the jacket comprises one or more pneumatic or hydraulic bladders. The pneumatic or hydraulic bladders are linked to a pump, and the pump fills the bladders with fluid and withdraws the fluid in a cycle to match beats of the heart to assist contraction and pumping of the heart in systole or to assist expansion and filling of the heart in diastole.